What Is Arm Pump?
If you ride bikes, whether that’s motocross, enduro, MTB or road racing the likelihood is that you’ve experienced it! Arm pump is one of the most talked about exercise induced conditions associated with two wheeled action sports. But what actually is it and what is the root cause?
Chronic Exertional Compartment Syndrome (CECS)
According to the literature, the underpinning condition resulting in the onset of ‘arm pump’ related symptoms is Chronic Exertional Compartment Syndrome (CECS).
CECS is defined as an increase in intracompartmental pressure within the muscle fascia, resulting in reduced blood flow and tissue perfusion to the affected area (Winkes et al., 2012). As less oxygen is able to reach the muscle, we typically observe a build-up of lactate and hydrogen ions.
Symptoms include ischemic pain, muscle hardening, functional loss and occasionally neurologic disturbances (Liu et al., 2017). Symptoms tend to resolve completely between periods of activity and return once the activity is resumed.
Why Does CECS Occur When I’m Riding My Bike?
Whilst controlling a bike both hands and forearms undergo enduring isometric contractions whilst continually gripping, correcting and stabilising the handlebars (subject to varying degrees of vibration, depending on the discipline). Particularly in motorsport, we also see extensive use of the ‘throttle’ which places even more stress on the forearm flexor compartment of the right arm.
Such actions cause increased blood flow to the working muscles in the hands and forearms. The muscles sit within a compartment and are wrapped in non-elastic connective tissue called fascia. As more blood is transported to the muscles, we see an increase in compartmental pressure as the fascia is unable to expand in line with the increased blood volume to the area (Mohler et al., 1997).
As pressure continues to rise within the compartment, deoxygenated blood set to leave the area becomes compromised (unable to leave). At this point oxygenated blood is still entering the muscle whist deoxygenated blood is unable to leave, thus increasing the compartmental pressure even further (Grange et al., 2009).
Eventually blood flow to the muscles is significantly reduced, causing oxygen deprivation. In conditions of low oxygen availability pyruvate is converted into lactic acid in a metabolic reaction called anaerobic glycolysis (Melkonian and Schury, 2019). With this being said, lactic acid quickly disassociates into lactate and a hydrogen ion within the muscle. Commonly people associate muscle fatigue, pain and dysfunction with the presence of lactic acid however it’s actually the increased presence of hydrogen ions (reducing the PH of the blood) that leads to muscle acidosis and therefore muscular fatigue, dysfunction and ischemic pain. Swelling, pain and muscle dysfunction can reach levels that give riders no choice but to discontinue their race or training session.
2 Simple Nutritional Tips To Help prevent Arm Pump
Hydration :When in a fully hydrated state we are able to maintain optimal blood plasma volume and osmolality levels. This ensures blood can be easily pumped around the body to transport nutrients and metabolic waste products to and from the working muscles.
- When in a dehydrated state, blood plasma volume is reduced which compromises blood flow. A reduced plasma volume gives blood a thick and viscous characteristic which typically results in an increased heart rate and decreased stroke volume as the body has to work even harder just to ensure this thicker blood is pumped around the body (Shirreffs, 2005). By staying hydrated, you can ensure your blood plasma volume remains at an optimal level, allowing it to be easily transported around the body! For more information on the importance of hydration read our article.
Nitrates :Many top level athletes use nitrate supplementation strategies to help prevent the onset of arm pump. When ingested, inorganic nitrates are reduced to nitrite before being further reduced to nitric oxide (Jones, 2014).
- Nitric oxide is a powerful signalling molecule that plays a role in several vascular and cellular functions within the body. Examples include blood vessel dilation, the regulation of mitochondrial biogenesis, glucose and calcium homeostasis, and muscle contractility. It must also be noted that a key effect of dietary nitrates is a reduction in the oxygen cost of exercise (Hord et al., 2009; Stamler and Meissner, 2001).
- The exact mechanism by which nitrate supplementation helps to reduce the onset of arm pump has not yet been consolidated within the literature. A likely theory is that elevated nitric oxide levels will help reduce the onset of arm pump by increasing blood flow to and from the muscles. This is achieved through increased vasodilation (widening) of the blood vessels thereby the increasing the volume of blood and therefore oxygen made available for the working muscles. As more oxygen is made available for the muscles, the onset of anaerobic glycolysis and it’s acidic by-products is delayed during exercise. For more information on nitric oxide and nitrates read our article.
- If you're looking for an easy, great tasting way to increase your nitrate consumption, check out our new Pre-Load Nitrate Blend today!
Grange, J.T., Bodnar, J.A. and Corbett, S.W., 2009. Motocross medicine. Current sports medicine reports, 8(3), pp.125-130.
Hord, N.G., Tang, Y. and Bryan, N.S., 2009. Food sources of nitrates and nitrites: the physiologic context for potential health benefits. The American journal of clinical nutrition, 90(1), pp.1-10.
Jones, A.M., 2014. Dietary nitrate supplementation and exercise performance. Sports medicine, 44(1), pp.35-45.
Liu, B., Barrazueta, G. and Ruchelsman, D.E., 2017. Chronic exertional compartment syndrome in athletes. The Journal of hand surgery, 42(11), pp.917-923.
Mohler, L.R., Styf, J.R., Pedowitz, R.A., Hargens, A.R. and Gershuni, D.H., 1997. Intramuscular deoxygenation during exercise in patients who have chronic anterior compartment syndrome of the leg. JBJS, 79(6), pp.844-9.
Melkonian, E.A. and Schury, M.P., 2019. Biochemistry, anaerobic glycolysis.
Shirreffs, S.M., 2005. The importance of good hydration for work and exercise performance. Nutrition reviews, 63(suppl_1), pp.S14-S21.
Stamler, J.S. and Meissner, G., 2001. Physiology of nitric oxide in skeletal muscle. Physiological reviews, 81(1), pp.209-237.
Winkes, M.B., Luiten, E.J., van Zoest, W.J., Sala, H.A., Hoogeveen, A.R. and Scheltinga, M.R., 2012. Long-term results of surgical decompression of chronic exertional compartment syndrome of the forearm in motocross racers. The American journal of sports medicine, 40(2), pp.452-458.